1. Field of the Invention
The present invention relates to a conveying apparatus which conveys a sheet via a conveying path including a curved portion and which corrects the direction of the sheet so that a side of a leading end of the sheet is orthogonal to a conveying direction, and a recording apparatus with the conveying apparatus mounted therein.
2. Description of the Related Art
In a known configuration of recording apparatuses represented by printers, copiers, and facsimile machines, sheets are conveyed using a conveying path with a curved internal space in order to reduce the size of the apparatus. In such a recording apparatus, a sheet may be pushed hard against an outer side of the conveying path due to the rigidity of the sheet and thus conveyed while being subjected to great conveying resistance. This increases the likelihood of causing the sheet to skew. Thus, such a recording apparatus desirably performs an operation of correcting the direction of the sheet so that a side of a leading end of the sheet is orthogonal to a conveying direction, what is called an skew correcting operation, before recording an image on the sheet. A known common skew correcting operation reverses a main conveying roller (roller) engaged with the sheet. During the skew correcting operation, a loop (flexible portion) of the sheet is formed in the internal space of the conveying path. The loop comes into abutting contact with the outer side of curvature of the conveying path. Then, a force is exerted in conjunction with the abutting contact and causes a leading end of the sheet to be pushed into the main conveying roller. Japanese Patent Application Laid-Open No. H08-157107 discloses an apparatus that can adjust the above-described pressing force according to the rigidity of the sheet. The apparatus disclosed in Japanese Patent Application Laid-Open No. H08-157107 includes an upstream guide formed of a thin elastic plate and a downstream plate formed of a rigid plate and biased toward an inner side of the conveying path by a spring; the upstream and downstream guides are arranged on the outer side of a curvature of the conveying path. In this apparatus, during the skew correcting operation, less rigid sheets come into abutting contact with the upstream guide and are pushed into an skew correcting roller by the elastic force of the upstream guide. More rigid sheets come into abutting contact with the downstream guide and are pushed into a registration roller by a downstream elastic force that is greater than that of the upstream guide. During the skew correcting operation, the apparatus disclosed in Japanese Patent Application Laid-Open No. H08-157107 provides a space in the conveying path in which the sheet is deflected or flexed and can push the sheet into the registration roller with an appropriate force according to the rigidity of the sheet.
When a conveying operation and an skew correcting operation are performed within a curved conveying path in the same manner as that of the apparatus disclosed in Japanese Patent Application Laid-Open No. H08-157107, a narrow conveying path (a short distance between the inner guide and the outer guide) facilitates the abutting contact of the loop of the sheet with the conveying path and is thus suitable for the skew correcting operation. However, in this case, conveying resistance of the sheet is increased, possibly affecting the conveying operation. In contrast, a wide conveying path (a long distance between the inner guide and the outer guide) serves to reduce the conveying resistance of the sheet and is thus suitable for the conveying operation. However, this makes the abutting contact of the loop of the sheet with the conveying path difficult, possibly hindering the skew correcting operation from being stably achieved.